linux-kernel - Re: [RFC PATCH v1 4/6] PM / devfreq: event: support rockchip dfi controller

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Message-ID: <20160603165426.GC21013@ulmo.ba.sec>
Date:	Fri, 3 Jun 2016 18:54:26 +0200
From:	Thierry Reding <thierry.reding@...il.com>
To:	Lin Huang <hl@...k-chips.com>
Cc:	heiko@...ech.de, mark.yao@...k-chips.com, myungjoo.ham@...sung.com,
	mturquette@...libre.com, sboyd@...eaurora.org,
	linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org, airlied@...ux.ie,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	kyungmin.park@...sung.com, dianders@...omium.org,
	dbasehore@...omium.org, huangtao@...k-chips.com, typ@...k-chips.com
Subject: Re: [RFC PATCH v1 4/6] PM / devfreq: event: support rockchip dfi
 controller

On Fri, Jun 03, 2016 at 05:55:17PM +0800, Lin Huang wrote:
[...]
> +	ret = clk_prepare_enable(data->clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to enable clk: %d\n", ret);
> +		clk_disable_unprepare(data->clk);
> +		return ret;
> +	}

This is going to give you a large WARN. clk_prepare_enable() already
leaves the clock in a proper state when it fails (i.e. it calls
clk_unprepare() if the clk_enable() part failed), so calling
clk_disable_unprepare() upon failure is going to unbalance the
reference counts.

Thierry

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